This invention relates generally to the testing of vehicles for mechanical defects and tire problems that affect the safety and ride quality of vehicles and more particularly concerns a product useful for testing tires and chassis related problems while the tires are under the full weight of the vehicle and being driven and steered. One of the most troublesome problems in testing vehicles is simulating actual driving conditions similar to those when the problem appears. Of course, road testing of vehicles can be done but it involves risk of accidents and adverse weather and road noise makes many problems unnoticable. Also one cannot view the chassis components but has to observe from the passenger compartment. Testing vehicles inside of a building has been done. For example, some have used dynamometers and chassis dynamometers but such devices do not allow the tires to be steered since they have fixed parallel rollers each of which contact both tires of a single axle of a vehicle. Also when using a dynamometer or chassis dynamometer, both wheels on an axle are driven at the same time so that one wheel cannot be independently driven. Also since a vehicle is restricted in its position during use to avoid having the vehicle travel off the rollers of the dynamometer, the tires exert forces against the rollers.
Some devices have been used to inspect or test tires while not on a vehicle such as those shown in U.S. Pat. Nos. 3,589,182 to Burgett; 3,621,247 to Lide; 3,729,992 to Lichtman and 4,169,373 to Clark; et. al. However, these devices do not have the capability to test the tires on a vehicle or under normal operating conditions.
Other devices are used to align wheels but cannot be used when the wheels are steered such as those shown in U.S. Pat. Nos. 2,777,211 to Martin; 3,587,325 to Hunter; 3,812,592 to Haupt; 3,815,407 to Lavery and 3,908,280 to Murakami; et. al.
Still other devices are used to align wheels and adjust casters, but only have limited ability to steer and cannot be operated at high rates of speed such as sixty (60) to eighty (80) miles per hour as shown in U.S. Pat. Nos. 2,137,949 to Phelps; 3,187,440 to Merrill and 3,546,782 to Pereue; et. al.
When a vehicle is being viewed being driven down a street it will be noticed that each vehicle moves differently (bounce, sway, etc.) depending on the manufactured stiffness of the vehicle's chassis components. This is partly a result of the suspension stiffness and interaction of all suspension components of a vehicle. A sportscar is designed to quickly transmit road variations to the driver so that the driver can react quickly, while a town car is designed to absorb road deviations so that they will not be felt by the passengers. When the weight of a vehicle is removed from its wheels, the wheels will hang down at different angles and stresses as compared to the way they were positioned with the full weight of the vehicle on them. This abnormal angle of the wheels and suspension system of the vehicle changes the relationship of each connecting part and creates forces, sensations and noises which are different than when normal. The normal operating angle of a vehicle is defined as the relationship in degrees or stress that exists between each component in a suspension system of a vehicle while the tires of a vehicle are supporting the weight of the vehicle and are allowed to cycle. Thus, it would be desirable to develop a diagnostic device which would, in a safe controlled environment duplicate a vehicle's own problem symptoms under the vehicle's normal operating angles in order to greatly enhance the diagnosis of mechanical defects that otherwise could not be seen, felt or heard.
Accordingly it is an object of the invention to provide a diagnostic device which will allow for testing of a vehicle in a operational mode which will simulate actual driving conditions.
It is an object to provide a diagnostic device that will test a chassis, wheel, suspension, tires and tire treads of a vehicle under normal operating angles.
It is a further object to provide a diagnostic device that will perform the tests at sound levels low enough to allow the user to hear the location of the problems.
It is a further object to provide a diagnostic device that will perform tests while the tire is cycling and the vehicle is being steered.
It is a further object to provide a diagnostic device that will perform tests while only one wheel on an axle is cycled.
It is a further object to provide a diagnostic device that will allow testing of a vehicle with its wheels being cycled without chaining the vehicle.
It is a further object to provide a diagnostic device that is user friendly and has safety back ups which inhibit a vehicle from leaving the testing device.
It is a further object to provide a diagnostic device that will absorb most of the forces of a cycling or a cycling steered wheel therby allowing the vehicle's chassis to remain in one position, which represents a normal operating angle.
It is a further object to provide a diagnostic device that will absorb all forces of a cycling or a cycling steered wheel thereby allowing the vehicle's chassis to remain motionless, which represents a modified normal operating angle wherein a partially unweighed situation is simulated such as when a vehicle bounces on a road.